Toggle linkage check valve

ABSTRACT

A toggle linkage check valve including a housing having an inlet and an outlet and a sealing plug disposed within the housing and adapted for movement between a first, closed position for preventing flow of liquid between the inlet and the outlet, and a second, open position for substantially permitting flow of liquid between the inlet and the outlet. The check valve includes a spring assembly removably disposed within the housing. The sealing plug is mounted upon the spring assembly. The spring assembly includes a rod member and a means for biasing the rod member toward the sealing plug. In the first position of the sealing plug, the rod member lies substantially perpendicular to a plane of the sealing member across the inlet, and in the second position of the sealing plug, the rod member lies at an acute angle to the plane of the sealing member. The means for biasing acts upon the rod member to apply, to the sealing plug, a biasing force of a second degree less than the first degree, whereby the spring assembly acts upon the sealing plug to provide a maximum resistance against liquid flow from the inlet toward the outlet when the sealing plug is in the first, closed position and a lesser resistance against liquid flow when the sealing plug is in the second, open position.

BACKGROUND OF THE INVENTION

The invention relates to check valves and more particularly to valvesfor preventing back flow.

Check valves are provided in a conduit system to prevent the backwardsflow of liquid, e.g. in the event of a reduction or reversal of a supplypressure. In a typical water piping system in a home or other building,check valves are used to prevent back flow of potentially contaminatedwater from the building water system (e.g. water from a wash tubcontaining detergent or other cleaning agents, or water from a lawn orgarden hose contaminated with fertilizer or other chemicals) into thewater main, as may occur, e.g., due to a sudden loss of pressure in thewater main. Different valve systems have been designed for the purposeof assuring that a drop in supply pressure will result in the closing ofthe check valve in order to prevent back flow.

In one prior art back flow valve, the sealing plug is weighted to biasthe valve toward the closed position. Forward flow of a liquid undernormal pressure forces the valve into open position, but upon pressurereduction the weight aids in closing the valve. A weight biased valvetypically does not close quickly enough to avoid flow reversal whichslams the valve shut and creating a noisy hammering sound.

Referring to FIG. 1, another prior art check valve 1 has a sealing plug2 mounted upon a scissor assembly 4. Springs 6 are attached at bothsides of the scissor assembly 4 between the scissor hinge arms 8, 8'which are generally perpendicular to the plane P of the sealing plug 2in closed position. The springs are disposed generally at a 45 degreeangle to the flow of liquid, the bias of springs 6 serving to urge thescissor assembly 4 toward a compressed configuration, thereby forcingthe sealing plug 2 against the inlet 9 to positively close the valve.The forward flow of a liquid (arrow F) under normal pressure opens thevalve.

SUMMARY OF THE INVENTION

In one aspect, the invention is a toggle linkage check valve including ahousing having an inlet and an outlet and a sealing plug disposed withinthe housing and adapted for movement between a first, closed positionfor preventing flow of liquid between the inlet and the outlet, and asecond, open position for substantially permitting flow of liquidbetween the inlet and the outlet. The check valve includes a springassembly removably disposed within the housing. The sealing plug ismounted upon the spring assembly. The spring assembly includes a rodmember and a means for biasing the rod member toward the sealing plug.In the first position of the sealing plug, the rod member liessubstantially perpendicular to a plane of the sealing member across theinlet, and in the second position of the sealing plug, the rod memberlies at an acute angle to the plane of the sealing member. The means forbiasing acts upon the rod member to apply, to the sealing plug, abiasing force of a second degree less than the first degree, whereby thespring assembly acts upon the sealing plug to provide a maximumresistance against liquid flow from the inlet toward the outlet when thesealing plug is in the first, closed position and a lesser resistanceagainst liquid flow when the sealing plug is in the second, openposition.

One feature of the toggle linkage check valve is that the springassembly further includes a bracket positioned within the housing, thebracket having an inlet facing portion and an outlet facing portion. Thesealing plug is rotatably attached to the inlet facing portion of thebracket and the spring assembly is located between the outlet facingportion of the bracket and the sealing plug.

Another feature of the toggle linkage check valve is that the springassembly is detachable from the sealing plug.

Still another feature of the toggle linkage check valve is that thespring assembly is rotatably attached to the bracket.

Yet another feature of the toggle linkage check valve is that the springassembly is detachable from the bracket.

Still yet another feature of the toggle linkage check valve is that thespring assembly is rotatably attached to the sealing plug.

Another feature of the toggle linkage check valve is that the springassembly is detachable from the sealing plug and is detachable from thebracket.

Still another feature of the toggle linkage check valve is that thespring assembly includes a forward toggle member and a rear togglemember each having one set of two toggle extensions, a rod, upon whichone of the toggle members is slidably attached and the other of thetoggle members is fixedly attached, and a compression spring, coaxialwith the rod and located between the forward and rear toggle assemblies.

Another aspect of the invention is a toggle linkage check valveincluding a housing with an inlet and an outlet, and a bracket, havingan inlet facing portion and an outlet facing portion, the bracketlocated within and fixedly attached to the housing and including acurved spring assembly retaining member on the outlet facing portion.The toggle linkage check valve further includes a sealing plug, locatedinside the housing, having a closed position, wherein the sealing plugprevents flow between the inlet and the outlet, and an open position,wherein the sealing plug substantially permits flow between the inletand the outlet, and an arm, having a first end fixedly attached to thesealing plug and a second end rotatably attached to the bracket. The armincludes toggle retaining notches on a side of the arm opposite thesealing plug and between the first end and the second end. The togglelinkage check valve also includes a spring assembly including a forwardtoggle member and a rear toggle member each having one set of two toggleextensions, the sets of toggle extensions defining a plane, a nippleattached to the front of the forward toggle member, and a rod, to whichthe forward toggle member is fixedly attached and upon which the reartoggle member is slidably mounted. The rod is oriented perpendicular tothe plane of the toggle extensions. The toggle linkage check valvefurther includes a pin mounted to the outlet facing end of the rod, toprevent the rear toggle member from sliding from the rod and a spring,located between the forward and rear toggle assemblies and coaxial tothe rod, the spring biasing the rear toggle member toward the pin. Theforward toggle member is adapted for engagement with the toggleretaining notches such that the nipple presses against the center of anoutlet facing surface of the sealing plug. The rear toggle member isadapted for the engagement of the curved spring assembly retainingmember on the outlet facing portion of the bracket. The toggle linkagecheck valve is constructed whereby when the pressure of a liquid at theinlet exceeds a predetermined pressure, the sealing plug moves from theclosed position thereby permitting flow between the inlet and saidoutlet.

DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT

We first briefly describe the drawings.

FIG. 1 is a somewhat diagrammatic side section view of a prior art checkvalve;

FIG. 2 is a similar view of a toggle linkage check valve of theinvention;

FIG. 3 is a side view of the check valve element of the embodiment ofFIG. 2 in closed position;

FIG. 4 is a similar view of the check valve element of FIG. 3 in openposition;

FIGS. 5 and 5a are top and side views respectively of the springassembly of the check valve of FIG. 2;

FIGS. 6, 6a and 6b are plots of pressure versus liquid flow for a togglelinkage check valve of the invention, FIG. 6 relating to operation of a4 inch radius sealing plug, FIG. 6A relating to operation of a 6 inchradius sealing plug and FIG. 6B relating to operation of an 8 inchradius sealing plug;

FIG. 7 is a side view of the toggle linkage check valve of FIG. 2 infront uncoupled position; FIG. 7a is a top view of the bracket of thecheck valve with the spring assembly in the uncoupled as in FIG. 7; and

FIG. 8 is a similar view of another embodiment of the toggle linkagecheck valve of the invention in front uncoupled position, with the reartoggle fixably and rotatably attached to the curved spring assemblyretaining portion.

Referring to FIG. 2, a toggle linkage check valve 10 of the inventionconsists of a check valve assembly 12 mounted within a housing 14. Thehousing 14 defines an inlet 16 and an outlet 18, and the check valveassembly 12 is positioned adjacent the inlet 16. The housing 14 alsoincludes an access cover 19 which permits access to the check valveassembly 12. The check valve assembly is mounted in a manner such thatflow of liquid is substantially unimpeded in the direction from inlet 16toward outlet 18, but prevented from flowing in the reverse directionfrom outlet 18 toward inlet 16. Referring now also to FIGS. 3 and 4, thecheck valve assembly 12 consists of a sealing plug 20 mounted at theinlet end of an arm 22. The arm 22 is rotatably mounted at the inlet end34 of a mounting bracket 40. The rotatable attachment is obtained byalignment of slots in both sides of the outlet end of arm 22, with slots32 in both sides 36, 38 of the inlet end 34 of the mounting bracket 40.The outlet end of arm 22 rides upon a roller bearing 30 located betweenthe sides 36, 38 of the mounting bracket 40, the ends of the rollerbearing 30 resting within the slots of the mounting bracket. Thecombination of arm 22 and roller bearing 30 permits the sealing plug 20of the check valve assembly 12 to rotate (arrow R) between a firstclosed position (FIG. 3) and a second open position (FIG. 4). In closedposition, the sealing plug 20 is engaged against the inlet 16 to preventflow of liquid through the valve 10. In open position, the sealing plug20 is displaced from the inlet 16 to permit flow of liquid.

The mounting bracket 40 has a base portion 42 through which extend twotapped mounting holes 44 by which the mounting bracket 40 is secured tothe housing 14. The outlet end 46 of both sides 36, 38 of the mountingbracket 40 includes a curved spring assembly retaining portion 48, aboutwhich more will be said shortly.

The sealing plug 20 is biased toward the closed position against theinlet 16 by action of spring assembly 60. Referring now also to FIGS. 5and 5A, the spring assembly 60 includes a forward toggle member 74fixedly attached at one end of a rod 72. A rear toggle member 70 isslidably mounted on the rod 72 and retained by a retaining pin 76. Acompression spring 78 is disposed about the rod 72 and retained betweenthe forward toggle member 74 and the rear toggle member 70. The spring78 biases the rear toggle member 70 toward the retaining pin 76.

Toggle members 70, 74 are each generally cylindrical in shape andinclude a toggle extension 86 consisting of an inner retaining edge 80and an outer retaining lip 82 at each end of the cylinder. The curvedspring assembly retaining portion 48 of each side 36, 38 of the mountingbracket 40 engages between the inner retaining edge 80 and the outerretaining lip 82 of the corresponding side of the rear toggle member 70,thereby centering the rear toggle member 74 between the two curvedspring assembly retaining portions 48.

The inlet end of the arm 22 has two sides 26, 28, each defining toggleretaining notches 90. The forward toggle member 74 engages each of thetoggle retaining notches 90 between the inner retaining edge 80 and theouter retaining lip 82. A centering nipple 92 located on the forwardtoggle member 74 and along the axis of rod 72 rests against the outletfacing surface of the sealing plug 20.

The forward toggle member 74 working through the arm 22 and centeringnipple 92 acts as the main point of contact between the sealing plug 20and the spring assembly 60, as is shown in FIG. 3. When the sealing plug20 is in closed position, the points of contact between the springassembly 60 and the sealing plug 20 allow the spring 78 to bias thesealing plug 20 toward the closed position and provide resistanceagainst a liquid pressure from the inlet 16. Referring to FIG. 4, whenthe liquid pressure is sufficient to overcome the resistance of thespring assembly 60, the sealing plug 20 is moved backwards anddownwards, forcing the rod 72 to slide through the rear toggle assembly70. The sealing plug 20 is prevented from further backwards or downwardsmovement by engagement of the forward toggle member 74 against themounting bracket 40. In this position, liquid is allowed to flowrelatively unimpeded from the inlet 16 toward the outlet 18.

When the liquid pressure falls below a predetermined level, the springassembly 60 forces the sealing plug 20 upwards and forwards, as thesealing plug 20 assumes a closed position to seal the inlet 16. Theclosing of the inlet 16 prevents a back flow of liquid from occurring.

Referring to FIGS. 6, 6A, 6B, the plots show pressure versus flow ratefor different size toggle linkage check valves of the invention. Thespring assembly 60 acts upon the sealing plug 20 and provides maximumresistance against the flow of liquid through the inlet 16 when thesealing plug 20 is in closed position (designated on the graph by theletter `A`). A minimum resistance against the flow occurs when thesealing plug is in open position (designated on the graph by the letter`B`).

If repair or replacement of the toggle linkage check valve 10 isrequired, the spring assembly 60 is easily uncoupled from the sealingplug 20 and, if necessary, may be entirely uncoupled from the remainingportion of the toggle linkage check valve 10 as follows. First, theaccess cover 18 is removed, permitting access to the check valve 12through the housing 14. Second, the forward toggle member 74 is forcedbackwards to compress the spring 78 and forced up and out of the toggleretaining notches 90, until the forward toggle assembly is uncoupledfrom the arm 22 (FIGS. 7 and 7a). Referring to FIGS. 5, 5A, if thespring assembly 60 needs to be entirely uncoupled, the rear togglemember 70 is slid down and out from between the curved spring assembly,retaining portions 48, after the forward toggle member 74 has alreadybeen uncoupled.

Referring now to FIG. 8, in another embodiment of the invention, therear toggle extensions 86 are rotatably but not removably attached tothe curved spring assembly retaining portions 100. The spring assemblycan either be fixably attached to the curved spring assembly retainingportions 100 or to the toggle retaining notches, or removably androtatably attached to both.

The foregoing description has been limited to a specific embodiment ofthis invention. It will be apparent; however, that variations andmodifications may be made to the invention with the attainment of someor all of the advantages of the invention. Therefore, it is the objectof the appended claims to cover all such variations of and modificationsas come within the true spirit and scope of the invention.

What is claimed is:
 1. A toggle linkage check valve comprising:a housing having an inlet and an outlet; a sealing plug disposed within said housing and adapted for movement between a first, closed position for preventing flow of liquid between said inlet and said outlet, and a second, open position for substantially permitting flow of liquid between said inlet and said outlet; and a spring assembly removably disposed within said housing, said sealing plug mounted upon said spring assembly, said spring assembly comprising a rod member and a means for biasing said rod member toward said sealing plug, in said first position of said sealing plug, said rod member lying substantially perpendicular to a plane of said sealing member across said inlet, and in said second position of said sealing plug, said rod member lying at an acute angle to said plane of said sealing member, with said means for biasing acting upon said rod member to apply, to said sealing plug, a biasing force of a second degree less than said first degree, whereby said spring assembly acts upon said sealing plug to provides a maximum resistance against liquid flow from said inlet toward said outlet when said sealing plug is in said first, closed position and a lesser resistance against liquid flow when said sealing plug is in said second, open position.
 2. The toggle linkage check valve of claim 1 wherein said spring assembly further comprises a bracket positioned within said housing, said bracket having an inlet facing portion and an outlet facing portion, said sealing plug being rotatably attached to said inlet facing portion of said bracket and said spring assembly being located between said outlet facing portion of said bracket and said sealing plug.
 3. The toggle linkage check valve of claim 2 wherein said spring assembly is detachable from said sealing plug.
 4. The toggle linkage check valve of claim 3 wherein said spring assembly is rotatably attached to said bracket.
 5. The toggle linkage check valve of claim 2 wherein said spring assembly is detachable from said bracket.
 6. The toggle linkage check valve of claim 5 wherein said spring assembly is rotatably attached to said sealing plug.
 7. The toggle linkage check valve of claim 2 wherein said spring assembly is detachable from said sealing plug and is detachable from said bracket.
 8. The toggle linkage check valve of claim 1 wherein said spring assembly comprises:a forward toggle member and a rear toggle member each having one set of two toggle extensions; a rod, upon which one of said toggle members is slidably attached and the other of said toggle members is fixedly attached; and a compression spring, coaxial with said rod and located between said forward and rear toggle assemblies.
 9. A toggle linkage check valve comprising:a housing with an inlet and an outlet; a bracket, having an inlet facing portion and an outlet facing portion, said bracket located within and fixedly attached to said housing, said bracket including a curved spring assembly retaining member on said outlet facing portion; a sealing plug, located inside said housing, having a closed position, wherein said sealing plug prevents flow between said inlet and said outlet, and an open position, wherein said sealing plug substantially permits flow between said inlet and said outlet; an arm, having a first end fixedly attached to said sealing plug and a second end rotatably attached to said bracket, said arm including toggle retaining notches on a side of said arm opposite said sealing plug and between said first end and said second end;a spring assembly comprising: a forward toggle member and a rear toggle member each having one set of two toggle extensions, said sets of toggle extensions defining a plane; a nipple attached to the front of said forward toggle member; a rod, to which said forward toggle member is fixedly attached and upon which said rear toggle member is slidably mounted, said rod oriented perpendicular to the plane of said toggle extensions; a pin mounted to the outlet facing end of said rod, to prevent said rear toggle member from sliding from said rod; and a spring, located between said forward and rear toggle assemblies and coaxial to said rod, said spring biasing said rear toggle member toward said pin; said forward toggle member adapted for engagement with said toggle retaining notches such that said nipple presses against the center of an outlet facing surface of said sealing plug, said rear toggle member adapted for engagement of said curved spring assembly retaining member on said outlet facing portion of said bracket; whereby when the pressure of a liquid at said inlet exceeds a predetermined pressure, said sealing plug moves from said closed position thereby permitting flow between said inlet and said outlet. 